$(document).ready(function() {
	$('#draggable').draggable({
		revert : 'valid'  //drop 했을 경우 작동.
	});
	$('#target_draggable').draggable({
		revert : 'invalid'
	});

	$('#droppable').droppable({
		hoverClass : 'hover',
		drop : function() {
			$(this).addClass('drop').text('Drop Success');
		}
	});
});